Book excerpt: Reinhold Niebuhr's An Interpretation of Christian Ethics is both an introduction to the discipline and a presentation of the author’s distinctive approach. That approach focuses on a realistic (rather than moralistic) understanding of the challenges facing human individuals and institutions, and a call for justice—imperfect though it might be—as what love looks like in a fallen world. The book’s most distinctive aspect is the author’s insistence that perfect love and justice are unattainable in this world, yet they remain our most important goals.